Merge bitcoindevkit/bdk#837: Derive `PartialEq`, `Eq` on `SyncTime`

45d41416ede5d2e26a8ef4c2cac6f44d0346fb23 Derive `PartialEq`, `Eq` on `SyncTime` (Max Fang)

Pull request description:

  ### Description

  This enables e.g. `assert_eq!` comparisons of `SyncTime` in tests (we use this)

  ### Changelog notice

  Derived `PartialEq`, `Eq` on `SyncTime`

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  rajarshimaitra:
    ACK 45d41416ede5d2e26a8ef4c2cac6f44d0346fb23
  evanlinjin:
    ACK 45d41416ede5d2e26a8ef4c2cac6f44d0346fb23

Tree-SHA512: eb2dc87762c33874a3a521c2f020250e83401c0f0e784911de6139bc8bf8c56f40c93ad2aa93cf20058ba796efd050979bddc5414acdd6856003e7a9f88c75c6